The present invention relates to an engine starter, and more particularly, to an engine starter for conservation.
For environmental, resource and fuel conservation, under the designation xe2x80x9ceco-runxe2x80x9d, it is encouraged to be sure to turn OFF a vehicle engine, (i.e. stop idling) while waiting for traffic signal change. One developed technique includes placing the vehicle into an idling-stop condition, automatically, even without operation by the driver. Then, the engine is started automatically upon a start-up operation by the driver. In connection with such an eco-run technique, the starter is required to rapidly start an engine from the idling-stop condition to prevent traffic congestion and starter wear. The easiest way to accomplish this is to keep the starter pinion engaged with the engine ring gear.
This technique is disclosed, for example, in JP-A No. Hei 8-26117. However, if the pinion and the ring gear are constantly meshed, noise is generated by the engagement of both gears during vehicular running and the service life of the small diameter pinion, also having a small number of teeth, is shortened.
In view of such, JP-A No. Hei 11-30139 describes a starter solenoid coil being energized during the idling stop condition, thereby allowing the pinion to engage the ring gear, such that during engine start-up, the pinion is engaged with the ring gear and driven and rotated by a motor. However, this publication only provides: xe2x80x9ca solenoid for controlling the engagement of the starter pinion is energized to mesh the pinion with the ring gearxe2x80x9d during the idling stop condition.
However, mere energization of the solenoid often fails to engage the pinion with the ring gear. More particularly, the pinion is pushed out when the starter solenoid is energized, but if the teeth position of the pinion and of the ring gear are not coincident, the pinion and the ring gear will abut each other at the respective end faces and the pinion will not mesh with the ring gear. Therefore, with only the information disclosed in the above publication, it is impossible to bring the pinion into positive engagement with the ring gear for start-up.
Another technique to reduce engine starting time includes engaging a pinion with the ring gear beforehand with a pinion actuator. However, in the rest position (power OFF), the pinion is disengaged from the ring gear. So, during the idling stop condition, the pinion actuator must be turned ON to keep the pinion engaged with the ring gear, requiring constant electric power during idling which drains the battery especially when not being charged as the engine is not running.
In light of these and other drawbacks, the present invention utilizes a starting step and a restoring step in this order. In the preliminary starting step, the starter pinion is pushed out at least halfway by a push-out means to abut the pinion against or mesh with the ring gear. Pushing out the pinion moves the pinion axially toward the ring gear, including pushing the pinion out when seen from the motor side and pulling the pinion into the motor side. In the starting step (the second step), the pinion is rotated by a starter motor and meshed with the ring gear. Then, the engine is cranked and started. In the restoring step (the third step), the pinion is restored to its original position spaced away from the ring gear.
Accordingly, in an idling stop condition, the preliminary step is carried out, in which the pinion is pushed out at least halfway toward the ring gear by the push-out means of the starter. As a result, the starter pinion abuts or meshes with the ring gear. In many cases, the pinion teeth and the ring gear teeth are not positionally coincident, and the pinion abuts an end face of the ring gear and is pushed against the ring gear by the push-out means. However, if the pinion teeth and the ring gear teeth are positionally coincident, the pinion is pushed out sufficiently deep and meshes with the ring gear.
Next, if the vehicle driver releases the brake, the idling stop condition is cancelled and the starting step is carried out, rotating the pinion. Then, where the pinion abuts the ring gear in the above preliminary step, the pinion meshes with the ring gear during its one-pitch rotation and is further pushed into a sufficiently deep engagement with the ring gear. When the pinion meshes with the ring gear, since the pinion has already been pushed against the ring gear, the pinion engages the ring gear when it begins to rotate. This reduces engaging shock to an extremely slight degree. Conversely, when the pinion is already meshed with the ring gear in the preliminary step, the pinion rotates the ring gear immediately. In this way, after the pinion has meshed with the ring gear, the engine is cranked and started by a motor driving the pinion and the ring gear.
Lastly, the restoring step is carried out upon engine start-up, whereby the starter pinion is restored to its original position spaced away from the ring gear. Therefore, during normal engine operation, the pinion is spaced away from the ring gear and does not produce an engaging noise or wear. In principle, the restoring step is carried out after engine start-up, but the engine may not be started even after going through the starting step, though this is rarely the case. Therefore, the restoring step can be carried out also in such a case. However, the starter system preferably immediately re-starts.
In the preliminary step, the pinion abuts an end face of the ring gear or is meshed with the ring gear. Therefore, even if when the pinion starts rotating in the starting step, engaging shock is extremely small. Or, if the pinion is already engaged with the ring gear, no engaging shock occurs. As a result, noise and vibration is reduced and durability of the entire starter including the pinion is increased.
Secondly, in the preliminary step, the pinion abuts or engages the ring gear, as noted earlier. In the starting step, therefore, the pinion shifts to its engaged state with the ring gear immediately from its abutted state against the ring gear. Or, when the pinion is already meshed with the ring gear in the preliminary step, the engine is cranked upon rotation of the pinion. As a result, the engine is rapidly started.
Thirdly, in the restoring step, after engine start-up, the pinion returns to its original position and leaves the ring gear, so that during normal engine operation, the pinion is spaced away from the ring gear. Thus, the pinion does not rotate during normal engine operation and therefore the durability of the starter including the pinion is improved. Also, the quietness during vehicular operation is improved because the pinion does not generate an engaging noise during vehicular running. Thus, according to the engine starting method in an idling stop condition, engaging shock of the pinion is diminished and the engine is started rapidly from an idling stop condition.
In another aspect, the preliminary step includes a meshing step where the starter motor is energized for a very short time, causing the pinion to turn slightly and thereby keeping the pinion engaged with the ring gear. Accordingly, even if the starter pinion is once abutted against an end face of the ring gear in the preliminary step, the pinion can be kept engaged with the ring gear by energizing the starter motor for only a very short time in the meshing step. More specifically, if the motor is energized for only a very short time to turn the pinion only a little, since the pinion already abuts the ring gear, the pinion turns to an angular position where it meshes with the ring gear, and both are meshed. In this case, the pinion does not have to turn fully once. Instead, the pinion need to only turn to an angular position corresponding to one pitch of the pinion teeth. Alternatively, the short-time energization for the motor may be repeated plural times, and in this case a single turning angle of the pinion may be less than one pitch.
In the meshing step, the energization time for the motor is very short, so that the turning angular velocity of the pinion is very low in comparison with the starting step and the pinion turns slowly into mesh with the ring gear. As such, there is little engaging shock of the pinion and the durability of the starter is further improved. Besides, since the engaging shock is not sensed at all by occupants of the vehicle, there is no fear that the occupants may have any offensive feeling caused by the engaging shock.
Thus, if the meshing step is carried out in the preliminary step, the pinion is already in a sufficiently deep mesh with the ring gear when the starting step is carried out after termination of the idling stop condition. In the starting step, therefore, there is no engaging shock, whereby the noise and shock during start-up are suppressed and the durability of the starter is improved. Also, since the pinion is already meshed with the ring gear, the engine is cranked as soon as the starting step begins and thus the engine start-up is effected more rapidly.
According this second means, therefore, in addition to the foregoing effects attained by the first means, the quietness during engine start-up and the durability of the starter are further improved, and the starting of the engine becomes more rapid.
In another aspect, the pinion is brought into mesh with the ring gear beforehand to shorten the time required for starting the engine from the idling stop condition, thereby suppressing electric power consumption. The pinion actuator is disengaged upon engine start-up and the pinion is disengaged from the ring gear against the biasing force of the biasing means.
In the idling stop state, the pinion is meshed with the ring gear with the biasing force of the biasing means. Thus, the rest position is where the pinion is meshed with the ring gear with the biasing force of the biasing means. Even if the pinion meshes with the ring gear during engine stop, electric power is not consumed. Therefore, even if the vehicle stop time becomes long due to idling, or the vehicle stop frequency increases due to traffic congestion, battery consumption is suppressed.
Also, since the pinion meshes with the ring gear during idling stop, no meshing time is needed during engine start-up and hence the time required for engine starting from an idling stop condition is shortened.
In another aspect, when the pinion is disengaged from the ring gear, the pinion is kept disengaged from the ring gear by the mechanical engaging means, whereby no energy is needed for disengaging the pinion from the ring gear during operation of the engine. Consequently, current consumption is suppressed.
According to the means of claim 3, when the engine stops, the releasing actuator is operated to bring the pinion into mesh with the ring gear, whereby with a small power consumption it is possible to let the pinion return to a rest position (engaged position with the ring gear).
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.